Manufacture of motor fuel



Dec. 22, 1942. F. M. McMlLLAN MANUFACTURE OF MOTOR FUEL Filed NOV. 29,1941 L & O. C 1 5; *d'

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\nv zni"or: Frank M. McMman Patented Dec. 22, 1942 MANUFACTURE OF MOTORFUEL Frank M. McMillan, Berkeley, Calif., assignor to Shell DevelopmentCompany, San Francisco, Calif., a corporation of Delaware ApplicationNovember 29, 1941, Serial No. 420,999

13 Claims.

This invention relates to the production of high anti-knock hydrocarbonmotor fuel fractions.

The invention provides a more efficient and economical method forobtaining branched-chain hydrocarbons from straight-chain hydrocarbonmixtures such as natural gasoline, low-boiling fractions of straight-rungasoline, and relatively low-boiling olefinic fractions obtained byfractionating the distillate products of thermal or catalytichydrocarbon conversions. A method whereby these materials can be treatedto obtain as substantially the sole products of the process, hydrocarbonfractions consisting essentially ofsingle branched-chain hydrocarbons ormixtures of branched-chain hydrocarbons having the same number of carbonatoms, is often greatly desired. Resort to the use of processes whereincracking is the principal reaction is, in such cases, undesirable sincethe materials treated are converted to a wide range of hydrocarbons ofwhich but a relatively small part may comprise the desiredbranched-chain hydrocarbons. The use of processes wherein isomerizationmethods available heretofore are used is often unsatisfactory, since inthese processes the isomerization of higher hydrocarbons such as thosehaving from five to ten carbon atoms to the molecule, particularlypentane, is generally unavoidably accompanied by hydrocarbondecomposition. The extent to which this hydrocarbon decomposition isencountered in these processes often renders the economical andefficient production of only the desired branched-chain hydrocarbons ona large scale difficult, if not impossible.

An object of the present invention is the provision of an improvedprocess for the production of branched-chain hydrocarbons highlydesirable as components of high anti-knock hydrocarbon motor fuels, fromhydrocarbon mixtures predominating in straight-chain hydrocarbons. Amore specific object of the invention is an improved process for theproduction of high anti-knock motor fuel fractions whereinstraight-chain hydrocarbons having from four to ten carbon atoms to themolecule are converted more efficiently to higher-boiling branched-chainhydrocarbons in the absence of any substantial hydrocarbondecomposition. A still further object of the invention is the provisionof an improved process for the production of higher-boiling hydrocarbonfractions predominating in branched-chain hydrocarbons having the samenumber of carbon atoms to the molecule from lower-boiling straightchainhydrocarbons.

In the improved process of the invention, a

mixture of substantially parailinic hydrocarbons is introduced into afractionating zone wherein a fraction predominating in normal butane andat least one fraction predominating in a straightchain hydrocarbonhaving from five to ten carbon atoms to the molecule are segregated. The

butane fraction is catalytically converted to isobutane. The higherhydrocarbon fraction or fractions are admixed with efiluence of thebutane conversion zone and subjected to isomerizing conditions at whichthe higher hydrocarbon or hydrocarbons are converted to branched-chainisomeric hydrocarbons in the absence of any substantial hydrocarbondecomposition. Isomerization products are returned to the fractionatingzone, wherein fractions predominating in branched-chain hydrocarbons aresegregated. At least a part of the branched-chain hydrocarbons thusobtained are admixed with an oleflnic hydrocarbon fraction, and theresulting mixture subjected to alkylating conditions. Saturatedhydrocarbons originally present in the oleflnic fraction and unreactedbranched-chain hydrocarbons are separated from the products ofalkylation and passed to the fractionating zone, in which the paraffiniccharge and isomerization products are fractionated.

In order that the invention may be more readily understood, it will bedescribed in detail with reference to the attached drawing showing oneform of apparatus suitable for carrying out the process of theinvention. 1 w

Referring to the drawing, a mixture o'f'sub stantially parafiinichydrocarbonssuch as, for

example, natural gasoline or a straight-run gasoline, is drawn from anoutside source and forced by means of pump I through line 2 into afractionating zone. In the drawing, fractionators 3, 4, and 5 are shownas constituting this fractionating zone. It will be understood that inactual practice more than three fractionators will generally be used toeffect the indicated fractionation. Within fractionator 3, materiallower-boiling than C4 hydrocarbons is removed overhead through valvedline 6. A fraction consisting essentially of butane is separated andforced through line I by means of pump 8, into fractionator 4. Afraction consisting essentially of a paraflin hydrocarbon having from 5to 10 carbon atoms to the molecule, for example pentane, is alsoseparated within fractionator 3 and forced through line 9 by means ofpump l0 into fractionator 5. Higher-boiling hydrocarbons are eliminatedfrom the lower part of fractionator 3 through valved line H. Withinfractionator 4, isobutane is separated as avapor fraction from normalbutane, and within fractionator 5 isopentane is separated as a vaporfraction from normal pentane.

other aluminous and/or silicious adsorptivema- 1 terials. Modifiedcatalysts of this type,- such as the mixture of an aluminum halide withother metal halides in either the solid 'or molten state may be used.Particularly eflective catalysts comprise a mixture of aluminum chloridedissolved in a mixture of molten metal halides such, for instance, asmolten mixtures comprising The temperature to be maintained withinreaction chamber l6 may range, for example, from about 50 C. to about300 C., and preferably from about 100 C. to about 200 C. Under theseconditions, butane will be converted to isobutane in its passage throughreaction chamber IS.

The isomerization reaction in the presence of these catalysts ispreferably carried out in the presence of a free hydrogen halidepromoter such as, for example, hydrogen chloride. Hydrogen chloride istherefore introduced into line ll through line H: Generally,concentrations of hydrogen chloride in the order of from about 2% toabout 10% by weight of the charge to the butane isomerization zon aresufficient. Larger or smaller amounts may, however, be used.

Normal pentane withdrawn from the lower part of fractionator 5 is forcedthrough line 19 and heater 20 by means of pump 2| into a secondisomerizing zone such as, for example, a reaction chamber 22. Withinreaction chamber 22, normal pentane is contacted with an aluminum halideisomerization catalyst, preferably selected from those described above.Although but one reaction chamber is shown in the drawing asconstituting each of the isomerization zones, it is to be understoodthat more than one reaction chamber or reactor may be used in each ofthe zones.

It is well known that butane, the first member of the isomerizablehydrocarbons, is, in relation to its higher-homologues, comparativelystable. It may be treated under relatively severe conditions with evenhighly active isomerization catalysts with only minor amounts ofdecomposition. The higher hydrocarbons, such as those having from fiveto ten carbon atoms to the molecule, and especially pentane, however,are particularly prone to undergo decomposition in the presence ofisomerization catalysts. By th term decomposition as used throughoutthis specification and the attached claims is meant the rupture ofcarbon to .carbon and/or carbon to hydrogen bonds of the hydrocarbonmolecule, to result in the formation of hydrocarbons of lower molecularweight than the hydrocarbon being isomerized. When these higherhydrocarbons are isomerized in accordance with the methods utilizedheretofore, an appreciable amount of isomerization can, under certainconditions, be attained. The extent to which hydrocarbon decompositionis unavoidably encountered in these methods generally acts as a seriousdeterrent to the practical application of these processes to theisomerization of hydrocarbons having from five to ten carbon atoms tothe molecule. These decomposition reactions are detrimental not onlybecause they occasion considerable loss of .the hydrocarbon beingtreated by converting it to undesirable byproducts, but because theseby-products, even when formed in relatively small amounts, generallybring about rapid destruction of the activity of the isomerizationcatalyst. In the procass of the invention, these difficulties areavoided by catalytically isomerizing the hydrocarbons having more thanfour carbon atoms to the molecule in the presence of isobutane, whichhas been found to suppress hydrocarbon decomposition in the presence ofthe isomerization catalysts.

In the process of the invention, the entire effluence of reactionchamber 16 comprising isobutane, unreacted butane, and hydrogenchloride, is passed through line 23 into line I9, thereby admixing withthe normal pentane prior to the entry of the pentane into reactionchamber 22. The passage of the eiiiuence of reaction chamber is directlyinto reaction chamber 22 not only eliminates the need of separatefractionation and recycling of the products of the separate isomerizingzones, but permits the full utilization of the heat content of thisstream to aid in maintaining the desired temperature in reaction chamber22. Since the C4 hydrocarbon decomposition suppressor and the hydrogenhalide" promoter constitute the predominant part of the chargeto thepentane isomerizing zone, a considerable saving in-heating requirementis thereby attained. The temperature to be maintained within reactionchamber 22 will generally be somewhat lower than that maintained withinreaction chamber 16. 1t is to be pointed out, however, that the presenceof the butanes enables the pentane isomerization to be carried out attemperatures substantially in excess of those at which pentane can beisomerized at all economically in processes utilized heretofore. Thetemperature within reaction chamber 22 is maintained within the broadrange of, for example, from about 30 C. to about 150 C. The particulartype of catalyst used will determine to a substantial degree thetemperatures within this broader range which are preferrcd for any oneoperation. Thus, when isomerizing pentan with a solid, supportedaluminum halide catalyst, a temperature of from about 40 C. to about 60C. may suitably be used. When the pentane isomerization is executed inthe presence of a catalyst of the molten salt type, a higher temperatureof from about C. to about C. is generally preferred. Within reactionchamber 22, normal pentane will, under these conditions, be converted toisopentane, and due to the presence of isobutane the pentaneisomerization will be effected in the absence of any substantial pentanedecomposition.

Isomerization products comprising isobutan'e, lsopentane, I unreactednormal butane and pentane, and hydrogen chloride are withdrawn fromisomerizing zone 22 and passed through line 24 and cooler 25 into anaccumulator 26. In passing through cooler 25, the reaction products arecooled to a temperature sufliciently low to effect the condensation ofat least a substantial part of the C4 hydrocarbons. Additional coolingmeans not shown in the drawing may be utilized if desired. Condensedproducts comprising C4 and C5 hydrocarbons are forced by means of pump21 from accumulator 26 through line 28, to a stripping column 29.Gaseous materials comprising hydrogen chloride and uncondensedhydrocarbons are forced from accumulator 26 by means of compressor 30through line 3i, into stripping column 29. Within stripping column 28, anormally gaseous fraction comprising hydrogen chloride is separated froma liquid hydrocarbon fraction comprising C4 and Cs hydrocarbons. 'A highpressure, for example in excess of 350 lbs., is preferably maintained instripping column 29 to aid in eifecting the desired separation. Theliquidfraction comprising C4 and Cs hydrocarbons is recycled throughvalved line 32 to line 2, leading into fractionator 3. The

normally gaseous fraction comprising hydrogen chloride is eliminatedfrom stripping column 29 through valved line 31 and passed at least inpart through lines 34 and IT, into line H. Makeup hydrogen chloride isintroduced into the system through valved line 85, leading into line 34,as needed.

The amount of isobutane to be maintained within reaction chamber 22 mayvary considerably within the scope of the invention in accordance withthe particular catalyst used. Whereas normal butane has little, if any,effect in suppressing decomposition reactions in the presence 01supported aluminum halide catalyst, it does have a favorable eflect inthe presence of aluminum halide catalysts of the molten salt type.Therefore, when utilizing the molten salt type catalysts. this a dedeflect of the normal butane present in the e uence of reaction chamberl6 permits the maintenance of lesser amounts of isobutane in reactionchamber 22 than if a supported aluminum chloride catalyst were used.Maintenance of a molecular excess of isobutane within reaction chamber22 is, however, desirable. To aid in maintaining any desired proportionof isobutane to pentanes, controlled amounts of Cr hydrocarbons may berecycled, when needed, with the hydrogen chloride from stripping column29 through line 34. When recycling C4 hydrocarbons with the hydrogenchloride promoter, the greater amount of the gaseous stream recycledthrough line 34 can be by-passed through valved line 38 into line 23,and only a suiiicient' amount of the mixture passed into line I! toprovide the desired amount of promoter to reaction chamber I6, byjudicious control of valves 36 and 31. Means not shown in the drawingmay be used to recycle C4. hydrocarbons in a separate stream to reactionchamber 22, should this be required.

The effectiveness of isobutane in suppressing pentane decomposition inthe presence of an aluminum chloride catalyst is shown in the followingexamples:

. Example I A mixture of normal pentane and isobutane in equal molarproportions was treated at 90 C. under a hydrogen chloride pressure of50 lbs. per sq. in. with a molten salt catalyst having the followingcomposition in weight per cent: Alma-75%, ZllCl2-10%, NaCl-7.5%,KCl7.5%. Analysis of the products showed an 85% conversion of pentane toisopentane in mol per cent. Only a negligible amount of pentanedecomposition was observed. The remainder of the pentane charged wasunchanged.

Example II A mixture of pentane and isobutane consisting of 33% mol percent pentane and 66% mol per cent isobutane was passed over activatedalumina impregnated with aluminum chloride at a temperature 50 C. and apressure of 60 lbs. per sq. in. Hydrogen chloride in the amount of 1 molper cent of the hydrocarbon charge was added. At the end of thirty hoursof continuous operation, a conversion of normal pentane to isopentane of50 mol per cent was obtained with only a negligible amounLot-pentanedecomposition. The remainderbi the pentane charged was unchanged.

It is to be pointed out that the unusual effectiveness in suppressinghydrocarbon decomposition in the presence of the aluminum halideisomerization catalysts is apparently restricted to the C4 paraflinhydrocarbons and is not possessed by propane, ethane, or methane.

The isomerization reactions within chambers l6 and 22 may be executed ineither the liquid or the vapor phase. When effecting the isomerizationin the liquid phase, it is preferred to use a catalyst of the moltensalt type described above. Since normal butane aids in suppressing thehydrocarbon decomposition reaction in the presence of the molten salttype catalyst, a highly advantageous method of carrying out the processof the invention comprises the execution of the butane isomerization inchamber Ii in the presence of a supported aluminum halide catalyst, andthe isomerization of the higher hydrocarbon in chamber 22 in thepresence of a catalyst of the molten salt type. When executing theprocess of the invention in-this wise, the eilluent chamber l6 willgenerally suffice to eflect the complete suppression of any substantialhydrocarbon decomposition within chamber 22. The pressure to bemaintained within the isomerization zones may vary widely within thescope of the invention. Pressures in the order of from about 50 to about300 pounds have been found highly suitable. When operating in the liquidphase, a pressure sufllciently high to maintain the hydrocarbon in theliquid phase is maintained.

Isobutane is eliminated overhead from fractionator 40 through line 39. Asubstantially olefinic hydrocarbon fraction predominating inhydrocarbons having the saine number of carbon atoms to the molecule isdrawn from an outside source by means of pump 40 and forced through lineH into line 38, wherein it is admixed with the isobutane. The olefinichydrocarbon fraction may be obtained from any suitable source such as,for example, by fractionation of the distillate products of a thermal orcatalytic hydrocarbon conversion operation. These fractions, as they aregenerally more readily obtained, comprise the oleflne in admixture withthe paraflin hydrocarbon'having the same number of carbon atoms tothemolecule as the olefine. Thus, a suitable fraction comprises abutane-butylene fraction. The resulting mixture of isobutane, butylene,and butane is passed into an alkylating zone. The alkylating zone maycomprise an alkylation unit comprising one or several stages providedwith means for contacting the hydrocarbon stream therein with a suitablealkylation catalyst such as sulfuric acid or the like, and forseparating the product from the catalyst For the sake of simplicity, thealkylating zone is depicted in the drawing by reactor 42. Within reactor42, condltions are maintained to bring about the alkylation ofbranched-chain saturated hydrocarbons with olefines. Thus, the reactionmaybe carried out at a temperature in the range of, for exampie, fromabout 5 C. to about C. at a pressure sufficiently high to maintain thereactants in the liquid phase. A cooler or refrigerating means 43 ispositioned before reactor 42 to aid in maintaining the desiredtemperature. The rate at which the olefine fraction is introduction intothe system is controlled to maintain an excess of the less reactiveisoparafiin molecule relative to the olefinic hydrocarbon within thealkylating zone. It is to be understood that the manner in which thereaction is effected as well as the operating conditions employed, maybe varied to produce the results particularly desired.

Alkylation products, which, when treating isobutane with abutylene-butane fraction, comprise branched-chain hydrocarbons havingeight carbon atoms to the molecule, unconverted isobutane, and normalbutane originally present in the olefinic fraction, after having beenneutralized, are passed through line 44 into a stripping column 45.Within stripping column 45, unreacted isobutane and the normal butanewhich was originally present in the olefinic hydrocarbon fractioncharged to the system is separated as a vapor fraction from a liquidhydrocarbon fraction comprising the alkylate. The vapor fraction isremoved overhead from stripping column 45 through valved line 46, andforced in part or in its entirety by means of pump 49 through valvedlines 41 and 48 into line I, passing into fractionator 4. It is seenthat in the process of the invention both the paraflinic and olefinicconstituents of fractions such as the butylenebutane fractions which areusually available in abundance in many refinery operations are utilizedefficiently in the production of desired branched-chain hydrocarbonswithout prelimi nary separation of the olefinic and paraffinicconstituents. The alkylate, consisting essentially of branched-chainhydrocarbons having eight carbon atoms to the molecule, is withdrawnfrom stripping column 45 through valved line 50.

Isopentane withdrawn from the upper part of fractionator 5 throughvalved line 5| may be removed in part or in its entirety from the systemthrough valved line 52 as a final product. A part or all of theisopentane, which is itself a highly desirable motor fuel component, maybe passed through valved line 53 and combined with the alkylatewithdrawn from fractionator 45 through line 50. All, or a part of theisopentane, may be passed through lines 5! and 39 to reactor 42 to bealkylated with the olefine therein. A valved line 54 is provided for theelimination of any part or all of the isobutane from the system whenisopentane is passed to the alkylating zone.

The invention is not limited to the use of butane-butylene as theolefinic fraction, and other olefinic fractions such as, for example, apropylene, butylene, amylene, cyclopentene, cyclohexene, or higherolefinic fraction, may be used. When such fractions are used, thesaturated con stituents thereof are passed from stripping column 45,through line 4'! to line 2, leading to iractionator 3. If a hydrocarbonfraction comprising hydrocarbons of the same number of carbon atoms asthose passed through line 41 is being fractionated in fractionator 5,the hydrocar on stream flowing through line 41 is by-passed throughvalved line 55 into line 9.

Although the above-detailed description has been limited for the sake ofsimplicity to the iso merization oi the butane and pentane content ofthe parafiinic hydrocarbonmixture charged, it is to be understood that astraight-ohain parai'nnic hydrocarbon having from six to ten carbonatoms may be separated and isomerized instead of the pentane. Theinvention, furthermore, contemplates the separate isomerization, in thepresence of efiluence of the butane isomerization zone, of more than onestraight-chain hydrocarbon having from five to ten carbon atoms to themolecule. Though the invention is directed primarily to the productionof branched-chain hydrocarbons from mixtures predominating instraightchain hydrocarbons, it is not beyond the scope of the process toseparate a higher branched-chain saturated hydrocarbon within the chargefractionating zone and subject it to separate catalytic isomerization inthe presence of elfluence of the first isomerizing zone to a morehighly-branched isomer. The more highly-branched hydrocarbon thusobtained may, if desired, be passed to the alkylation zone. Theadditional isomerization and fractionating means which may be requiredfor the execution of these various modifications of the invention havebeen omitted from the drawing for the purpose of avoiding unduecomplexity. When a plurality of hydrocarbons having from five to tencarbon atoms are isomerized, any single, several, or all of theresulting branched-chain 'paraflin hydrocarbons produced in theisomerization steps may be passed'to the alkylating zone. Although butone alkylating unit is shown in the drawing, additional alkylating unitsmay be provided to effect the alkylation in separate units of isobutaneand one or more branched-chain saturated hydrocarbbns having from fiveto ten carbon atoms to the molecule. The process of the invention thusenables the production oi a wide variety of branched-chain hydrocarbonfractions optionally predominating in branched-chain hydrocarbons of thesame number of carbon atoms, with a minimum of operative steps and inthe absence of any hydrocarbon decomposition.

I claim as my invention:

1. In a process for the production of branchedchain hydrocarbons in theabsence of any substantial hydrocarbon decomposition, the steps whichcomprise fractionating a substantially parafiinic hydrocarbon mixturecomprising C4 and C5 hydrocarbons in a fractionating zone to separatefractions respectively rich in normal butane and normal pentanetherefrom, contacting the normal butane fraction at a temperature in therange of from about C. to about 200 C. with an aluminum halide catalystin a first isomerizing zone, contacting the pentane fraction inadmixture with the eiiluence of the first isomerizing zone at atemperature in the range of from about 40 C. to about C. with an aluminum halide catalyst in a second isomerizing zone, separating isobutaneand isopentane from the eflluence of the second isomerizing zone,contacting said isobutane and isopentane in admixture with a hydrocarbonfraction predominating in butylene and butane at alkylating conditionswith an alkylation catalyst, thereby reacting isobutane and isopentanewith butylene, separating butane, isobutane, and isopentane as a vaporfraction from the products of alkylation, and passing said vaporfraction to said fractionating zone.

In a process for the production of branchedchain hydrocarbon fractionsin the absence of any substantial hydrocarbon decomposition, the stepswhich comprise fractionating a substantially parafilnic hydrocarbonmixture comprising hydrocarbons having from four to ten carbon atoms tothe molecule in a fractionating zone to separate fractions respectivelyrich in normal butane and a higher saturated hydrocarbon having fromfive to ten carbon atoms to the molecule therefrom, contacting thenormal butane fraction at a temperature in the range of from about 50 C.to about 300 C., with an aluminum halide catalyst in a first isomerizingzone, contacting the higher hydrocarbon fraction in admixture with theeiiluence of the first isomerizing zone at a temperature in the range offrom about 30 C. to about 150 C. with an aluminum halide catalyst in asecond isomerizing zone, separating branched-chain hydrocarbons from theefiiuence of the second isomerizing zone, contacting the branched-chainhydrocarbons in admixture with a hydrocarbon fraction predominating inbutylene and butane at alkylating conditions with an alkylationcatalyst, thereby reacting branched-chain hydrocarbons with butylene,separating butane and unreacted branched-chain hydrocarbons as a vaporfraction from the alkylation products, and passing said vapor fractionto said fractionating zone.

3. In a process for the production of branchedchain hydrocarbonfractions in the absence of any substantial hydrocarbon decomposition,the steps which comprise fractionating a substantiallyparaffinichydrocarbon mixture comprising hydrocarbons having from four to tencarbon atoms to the molecule in a fractionating zone to separatefractions respectively rich in normal butane and a higher saturatedhydrocarbon having from five to ten carbon atoms to the moleculetherefrom, contacting the normal butane fraction at a temperature in therange of from about 100 C. to about 200 C., with an aluminum halidecatalyst in a first isomerizing zone, contacting'the higher hydrocarbonfraction in admixture with the efliuence of the first isomerizing zoneat a temperature in the range of from about 40 C. to about 50 C. with acatalyst comprising an aluminum halide and an adsorbent support materialin a second isomerizing zone, separating the branched-chain hydrocarbonsfrom the eiiiuence of the second isomerizing about 80 C. to about 110 C.with a molten salt mixture comprising an aluminum halide in a secondisomerizing zone, separating branchedchain hydrocarbons from theeflluence of the second isomerizing zone, contacting the branched-chainhydrocarbons in admixture with a hydrocarbon fraction predominating inbutylone and butane at alkylating conditions with an alkylationcatalyst, thereby reacting branchedchain hydrocarbons and butylene,separating butane and unconverted branched-chain hydrocarbons as a vaporfraction from the alkylation products, and passing said vapor fractionto said fractionating zone.

5. In a process for the production of branchedchain hydrocarbons in theabsence of any substantial hydrocarbon decomposition, the steps whichcomprise fractionating a substantially paraiiinic hydrocarbon mixturecomprising C4. and C5 hydrocarbons in a fractionating zone to separatefractions respectively rich in normal butane and normal pentanetherefrom, contacting the normal butane fraction under isomerizingconditions with an aluminum halide catalyst in a first isomerizing zone,contacting said pentane fraction in admixture with the efiiu'ence of thefirst isomerizing zone under isomerizing conditions with an aluminumhalide catalyst in a second isomerizing zone, separating isobutane andisopentane from the eiiluence of the second isomerizing zone, contactingsaid isobutane and zone, contacting the branched-chain hydrocarbons inadmixture with a hydrocarbon fraction predominating in straight-chainolefine and paraflin hydrocarbons of the same number of carbon atoms atalkylating conditions with an alkylation catalyst, thereby reactingbranchedchain hydrocarbons with the olefine, separating thestraight-chain paraffin and unreacted branched-chain hydrocarbons as avapor fraction from the alkylation products, and passing the vaporfraction to said fractionating zone.

4. In a process for the production of branchedchain hydrocarbonfractions in the absence of any substantial hydrocarbon decomposition,the

steps which comprise fractionating a substantially paraflinichydrocarbon mixture comprising hydrocarbons having from four to tencarbon atoms to the molecule in a fractionating zone to separatefractions respectively rich in normal butane and a higher saturatedhydrocarbon having from five to ten carbon atoms to the moleculetherefrom, contacting the normal butane fraction at a temperature in therange of from about 50 C. to about 300 C. with an aluminum halidecatalyst in a first isomerizing zone, contacting the higher hydrocarbonfraction in admixture with the effluence of the first isomerizing zoneat a temperature in the range of from isopentane in admixture with ahydrocarbon fraction predominating in butylene and butane at alkylatingconditions with an alkylation catalyst, thereby reacting isobutane andisopentane with butylene, separating butane, isobutane, and isopentaneas a vapor fraction from the products of alkylation, and passing thevapor fraction to said fractionating zone.

6. In a process for the production of branchedchain hydrocarbons in theabsence of any substantial hydrocarbon decomposition, the steps whichcomprise fractionating a substantially paramnic hydrocarbon mixturecomprising C4 and C5 hydrocarbons in a fractionating zone to separatefractions respectively rich in normal butane and normal pentanetherefrom, contacting the normal butane fraction under isomerizingconditions with an aluminum halide catalyst in a first isomerizing zone,contacting the pentane fraction in admixture with the efiiuence of thefirst isomerizing zone under isomerizing conditions with an aluminumhalide catalyst in a second isomerizing zone, separating isobutane andisopentane from, the effluence of the second isomerizing zone,contacting said isobutane and isopentane in admixture with a hydrocarbonfraction predominating in straight-chain olefine and paraffinhydrocarbons having the same number of carbon atoms at alkylatingconditions with an alkylation catalyst, thereby reacting isobutane andisopentane with said olefine, separating the straight-chain paraffin andunreacted branched-chain hydrocarbons as a vapor fraction from thealkylation products, and passing the vapor fraction to saidfractionating zone.

7. In a process for the production of branchedchain hydrocarbons in theabsence of any substantial hydrocarbon decomposition, the steps whichcomprise fractlonating a substantially paraffinic hydrocarbon mixturecomprising hydrocarbons having from four to ten carbon atoms to themolecule in a iractionating zone to separate fractions respectively richin normal butane and a higher saturated hydrocarbon having fromadmixture with a hydrocarbon fraction predominating in butylene andbutane at alkyiating condltions with an alkylation catalyst, therebyreacting branched-chain hydrocarbons with butylene, separating normalbutane and unreacted branched-chain hydrocarbons as a vapor fractionfrom the alkylation products, and passing the vapor fraction to saidiractionating zone.

13. In a process for the production of branched chain hydrocarbons inthe absence of any substantial hydrocarbon decomposition, the stepswhich comprise fractionating a substantially parafiinic hydrocarbonmixture comprising hydrocarbons having from four to ten carbon atoms tothe molecule in a fractionating zone to separate fractions respectivelyrich in normal butane and a higher saturated hydrocarbon having fromfive to ten carbon atoms to the molecule therefrom, contacting thenormal butane fraction in admixture with a hydrogen halide promoter atisomerizing conditions with an aluminum halide isomerization catalyst ina first isomerizing zone, contacting the higher hydrocarbon fraction inadmixture with the efliuence of the first isomerizing zone underisomerizing conditions with an aluminum halide catalyst in a secondisomerizing zone, separating hydrogen halide, isobutane, and a higherbranched-chain hydrocarbon from the eiiiuence of the second isomerizingzone, recycling a part of said isobutane to the second isomerizing zone,contacting the remaining isobutane and higher branched-chain hydrocarbonin admixture with a hydrocarbon fraction predominating in butylene andbutane at alkylating conditions with an alkylation catalyst, therebyreacting branchedchain hydrocarbons with butylene, separating normalbutane and unreacted branched-chain hydrocarbons as a vapor fractionfrom the alkylation products, and passing the vapor fraction to saidfractionating zone.

FRANK M. McMILLAN.

